Various types of rod guides have been devised for guiding a sucker rod within production tubing. Many rod guides are intended for use with a reciprocating sucker rod, and other rod guides are primarily intended for use with a rotating sucker rod. Some guides have utility for either a reciprocating rod or a rotating rod, although design considerations generally dictate that a sucker rod guide be primarily intended for one application.
Compared to commonly used beam pumps which are powered by a reciprocating sucker rod, progressive cavity pumps are generally able to deal with a high concentration of sand or other particulate in the recovered fluid. In many cases, however, rod guides for PC pumps wear excessively when subjected to the upwardly moving fluid and sand within the production tubing. The cost of replacing PC rod guides for these applications thus represents a significant cost to the well operator. Other rod guides have low erodeable wear volume, i.e., the volume of the guide radially exterior of the rod coupling is minimal, and wear of that excess material reduces the effectiveness of the guide. Other rod guides have poor flow characteristics, meaning that the flow channels around the guide result in a high pressure loss, thereby increasing the power required to pump the fluids to the surface. Other types of rod guides allow sand or other particles to become trapped or imbedded between components of the guide, thereby substantially contributing to premature wear of the guide.
Many rod guides designed for PC pumps include a rotor sleeve secured to the rod string and a stator sleeve positioned about the rotor sleeve. The stator sleeve conventionally has an elongate slot, which is spread apart to position the stator sleeve on the rotor sleeve. The stator is typically spaced about a cylindrical body of the rotor, and between upper and lower stop surfaces on the rotor. U.S. Pat. Nos. 5,191,938, 5,339,896, 5,755,284, 5,692,562 and 6,065,537 disclose rod guides for guiding a sucker rod intended for powering a downhole pump to pump fluids to the surface of a well.
The disadvantages of the prior art are overcome by the present invention, and an improved rod guide particularly suited for guiding a sucker rod powering a progressive cavity pump is hereinafter disclosed.